The biological acetabular reconstruction with bone allografts in hip revision arthroplasty.

BACKGROUND: Reconstructions in case of acetabular bone loss in hip revision arthroplasty are challenging. A few techniques have been proposed, with inconstant outcomes. Biological reconstructions using bone allografts may address the acetabular bone loss and restore the hip anatomy. Aim of this work was the description of the surgical technique and the evaluation of the outcomes using a regional arthroplasty register. MATERIALS AND METHODS: Minor or massive bone allografting was performed in hip revision arthroplasties in a tertiary center. Bulk allografts were used in severe acetabular bone losses. Fresh-frozen femoral heads were impacted in the bone cavity and porous cups were implanted; multihole sockets were used when necessary. In DeLee A zone, no grafts were used in order to reduce overstress graft resorption. The results were evaluated using a regional arthroplasty register, and a comparison with revisions without bone grafts was performed investigating re-revision rates and reasons for further revisions. RESULTS: At 10 years, acetabular revisions with bone allografts achieved a similar survival rate than revisions without bone grafts. The re-revisions occurred more frequently in revisions without bone allografts (10.8 vs. 9.7%). In the allograft cohort, septic loosening was lower (0.3 vs. 2.6%), whereas a higher rate of aseptic cup loosening was experienced (2.7 vs. 1.4%). CONCLUSIONS: Bone allografts may provide a good restoration of the acetabular bone stock and the hip biomechanics. Septic loosening does not seems a major concern, whereas a higher rate of aseptic cup loosening should be expected when bone grafts are used.

The experience of the RIPO, a shoulder prosthesis registry with 6-year follow-up.

BACKGROUND: Implant registries have proved valuable in assessing the outcomes of arthroplasty procedures. Moreover, by identifying lesser quality implants they have indirectly improved the quality of care. The registry of prosthetic shoulder implants was established in 2008. METHODS: It records information on all types of primary and revision arthroplasty procedures involving the glenohumeral joint, including reverse and total arthroplasty, hemiarthroplasty, resurfacing, removal, and any other surgical procedures that are required to manage these patients. The collected data include patient demographics, weight, height, operated side, cuff status, and diagnosis/reason for revision surgery, information on previous surgical procedures involving either shoulder, comorbidities, antibiotic and thromboembolic prophylaxis, blood transfusions, surgical approach, cuff repair procedures performed during arthroplasty, bone grafts, drains, and perioperative complications, and data about the prosthetic components implanted, including the fixation method. RESULTS: Procedures were performed on 3754 shoulders. They included 2226 RSA, 320 TSA, 730 HA, 233 resurfacing procedures, 245 revisions, and 77 "other" procedures. The survival curves of the implants are greater than 90%, and no differences were found among prosthesis from different manufacturers. The diagnosis that prompted to arthroplasty was: osteoarthritis in 60.9% of cases and fractures, bone necrosis, sequelae of fracture and rotator cuff tear arthropathy for the rest of implants. DISCUSSION AND CONCLUSION: This study describes the epidemiological data and mid-term implant outcomes of the shoulder arthroplasty procedures performed in our region, from 2008 to 2014, and compares them with published data from national registries of similar size. LEVEL OF EVIDENCE: III.

Albumin as marker for susceptibility to metal ions in metal-on-metal hip prosthesis patients.

Metal-on-metal (MoM) hip prostheses are known to release chromium and cobalt (Co), which negatively affect the health status, leading to prosthesis explant. Albumin (ALB) is the main serum protein-binding divalent transition metals. Its binding capacity can be affected by gene mutations or modification of the protein N-terminal region, giving the ischaemia-modified albumin (IMA). This study evaluated ALB, at gene and protein level, as marker of individual susceptibility to Co in MoM patients, to understand whether it could be responsible for the different management of this ion. Co was measured in whole blood, serum and urine of 40 MoM patients. A mutational screening of ALB was performed to detect links between mutations and metal binding. Finally, serum concentration of total ALB and IMA were measured. Serum total ALB concentration was in the normal range for all patients. None of the subjects presented mutations in the investigated gene. Whole blood, serum and urine Co did not correlate with serum total ALB or IMA, although IMA was above the normal limit in most subjects. The individual susceptibility is very important for patients' health status. Despite the limited results of this study, we provide indications on possible future investigations on the toxicological response to Co.

Vanadium release in whole blood, serum and urine of patients implanted with a titanium alloy hip prosthesis.

INTRODUCTION: Vanadium (V) is a minor constituent of the Titanium-Aluminum-Vanadium (TiAlV) alloy currently used in cementless hip prostheses. Present study aimed at verifying the correlation of vanadium levels among different matrices and assessing reference levels of the ion in a population of patients wearing a well-functioning hip prosthesis. METHODS: Vanadium was measured using Inductive Coupled Plasma Mass Spectrometry (ICP-MS) in whole blood, serum and urine of 129 patients implanted with a TiAlV-alloy hip prosthesis. RESULTS: The values in the serum were above the upper limit of the reference values in 42% of patients (29% in urine and 13% in whole blood). A good correlation among matrices was observed (p < 0.001). The cohort of patients (N = 32) complaining of pain or in which a loosening or damage to the prosthesis was assessed showed a significantly higher excretion of vanadium in urine as compared with the remaining asymptomatic patients (p = 0.001). The 95th percentile distribution of vanadium in the cohort of patients with a well-functioning prosthesis was 0.3 µg/L in whole blood, 0.5 µg/L in serum and 2.8 µg/L in urine, higher that in the unexposed population, especially for urine. CONCLUSIONS: The presence of a prosthesis, even though well-functioning, may cause a possible release of vanadium into the blood and a significant urinary excretion. The reference values of vanadium of the asymptomatic patients with titanium alloy hip prostheses supplied information regarding the background exposure level of the ions and their lower and upper limits.

Correlative light and scanning X-ray scattering microscopy of healthy and pathologic human bone sections.

Scanning small and wide angle X-ray scattering (scanning SWAXS) experiments were performed on healthy and pathologic human bone sections. Via crystallographic tools the data were transformed into quantitative images and as such compared with circularly polarized light (CPL) microscopy images. SWAXS and CPL images allowed extracting information of the mineral nanocrystalline phase embedded, with and without preferred orientation, in the collagen fibrils, mapping local changes at sub-osteon resolution. This favorable combination has been applied for the first time to biopsies of dwarfism syndrome and Paget's disease to shed light onto the cortical structure of natural bone in healthy and pathologic sections.

Polyethylene insert damage in unicondylar knee replacement: a comparison of in vivo function and in vitro simulation.

Modification of knee joint wear simulation methods has included 'anatomic attachment' of unicondylar knee replacements (UKR) onto synthetic femurs with material properties and morphology similar to human femurs. The present study assesses the effect of such modification by comparing the damage patterns on UKR polyethylene inserts after in vitro simulation using standard and modified simulation methods with those on inserts retrieved after in vivo function. Three groups of UKR inserts were evaluated after retrieval (Explant Group, n = 17) or after knee joint wear simulation with the components attached to standard metal blocks (Standard Group, n = 6) or synthetic femurs (Anatomic Group, n = 6). All UKR had similar non-conforming articular surfaces. Articular damage patterns (mode, frequency, and area) were quantified using digital image photogrammetry. Although some common damage modes were noted, knee joint wear simulation with standard or 'anatomic' attachment did not generate damage pattern sizes similar to the explanted UKR. A focal damage pattern consistent with contact between the metal femoral articular surface and the polyethylene inserts was evident on all inserts, but only the Explant Group had evidence of dispersed damage dominated by abrasive modes. Synthetic femurs added complexity to the wear simulation without generating wear patterns substantially more similar to those observed on retrieved inserts.

First hip arthroplasty register in Italy: 55,000 cases and 7 year follow-up.

The Register for Orthopaedic Prosthetic Implantation (RIPO) has been prospectively collecting data on hip prostheses performed in all the orthopaedic units in the region Emilia-Romagna since January 2000. The register aims to determine the characteristics of patients, evaluate the effectiveness of prostheses, and allow internal audit. Adherence to the register is compulsory (93% capture). By 31 December 2006 the register contained data on 35,041 primary total hip arthroplasty (THA), 14,613 hemiarthoplasties, and 5,878 revisions. All prosthetic components are registered on an individual basis. Survival analysis is done following the Kaplan Meier method. Cumulative survival rate at 7 years is 96.8% (95% CI: 96.4-97.1%) for THA and 97.6% (97.0-98.3%) for hemiarthroplasties. Multivariate analysis verified that survival of the THA is affected by pathology, where the worst conditions are rheumatoid arthritis, femoral neck fracture, and sequelae of coxitis or Paget's disease. Results are comparable to other major registers of Northern Europe and Australia.

A case report of fracture of ceramic head in total hip arthroplasty: histological and biochemical features of perimplant tissues.

The authors analyzed the case of a patient with a non-cemented hip prosthesis with a ceramic-ceramic coupling. As a consequence of trauma the head fractured. Although the patient could feel the joint grinding, there was no pain and he continued daily living activities for nearly six months, which led to marked wearing of the ceramic head. SEM analysis with microprobe showed 'planed' surfaces on the ceramic head, suggesting repeated movements between the fractured components. Inside the cone of the head, signs of TiAlV, which is an alloy of the prosthetic stem, could be seen. Periprosthetic tissues were packed with ceramic wear particles of sizes ranging between 0.2 and 10 microns, according to the harvest site. Metal and mixed particles were also found. IL1, IL6, IL8 and IL10 assays in the synovial liquid confirmed the inflammatory state and a modest induction of bone resorption, which was less than that observed in patients with loosened metal-polyethylene couplings. The humoral picture was compatible with the radiological aspect, which did not show marked signs of bone resorption. In revision surgery both ceramic components were replaced by a metal head and polyethylene liner. The clinical outcome after 12 months was very good.

Determination of crystallinity and crystal structure of Hylamer polyethylene after in vivo wear.

Hylamer polyethylene is a crystalline form of polyethylene of 70% crystallinity whereas conventional polyethylene (PE) has 50% crystallinity. Crystallinity is the percentage by weight of the crystalline phase present in the whole polymer, which comprises both amorphous and crystalline phases. Clinical experience has shown that Hylamer components used in joint prostheses, if sterilized by gamma rays in the presence of oxygen, are easily affected by wear, which leads to osteolysis. The authors have analyzed the crystallinity of polyethylene liners removed from seven patients who had received Hylamer polyethylene implants sterilized by gamma rays in air and had suffered prosthetic loosening, using Raman spectroscopy coupled with partial least squares (PLS) analysis. The results have been compared to those of two controls who had received Hylamer polyethylene implants sterilized by gamma irradiation in a nitrogen atmosphere. The crystal structure of wear particles released into the tissues from the Hylamer liners sterilized by gamma rays in air is also studied. The materials undergoing two different types of sterilization methods show different crystallinity values (71.50 vs. 69.43), but the crystallinity do not change according to wear (worn and unworn liner region). Both monoclinic and orthorhombic phases are present in the liner, while in wear debris prevalently monoclinic crystals are found in both types of sterilized liners. Different crystallinity rates can explain different wear rates observed in vivo.

Behavior of Hylamer polyethylene in hip arthroplasty: comparison of two gamma sterilization techniques.

Hylamer polyethylene was introduced in the 1990s as an alternative to conventional polyethylene. Its chemical and physical properties, and especially its high crystallinity, were claimed to improve resistance to wear. Initially Hylamer devices were sterilized by gamma radiation in air, then the technique was changed and gamma radiation was performed in the absence of oxygen. Clinical experience has shown the early loosening of some devices made from Hylamer. The aim of this study was to ascertain whether early wear and consequent osteolysis was linked to the sterilization method. We retrospectively compared 31 patients with hip prostheses with Hylamer liners sterilized by gamma radiation in air (group 1) with 30 patients with the same prosthesis, but sterilized in the absence of oxygen (group 2). The groups were similar for sex, age, disease, head diameter and material. Mean follow-up was 84 months and no clinical signs of failure were present. Radiographic measurement revealed that wear of group 1 was significantly greater than that of group 2 (0.23 mm/year vs 0.09 mm/year, p=0.001). Periacetabular and femoral osteolysis in group 1 was significantly greater than group 2. In conclusion, the method of sterilization might have influenced the outcome of Hylamer polyethylene liners.

Isolation and characterization of wear debris generated in patients wearing polyethylene Hylamer inserts, gamma irradiated in air.

Hylamer polyethylene was used in the early 1990s to make hip-joint components. Clinical experience has shown that these components, if sterilized by gamma rays in the presence of oxygen, are easily affected by wear, which then leads to osteolysis. The authors analyzed polyethylene wear particles in seven patients who had received Hylamer polyethylene implants sterilized by gamma rays in air and had suffered prosthetic loosening. The results were compared to those of six controls, who had received traditional polyethylene implants, sterilized by the same method. The frequency distribution of globular and fibrillar particles was similar in both groups (38.5% in Hylamer, 45.2% in controls). The globular particles in the Hylamer samples had a mean area of 0.12 microm2, which was significantly lesser than that of the controls (0.30 microm2). The width of fibrillar particles in the Hylamer samples was significantly lesser than that of the controls. Therefore, the two materials, despite undergoing the same type of sterilization, produced different types of wear, due to their different properties. In conclusion, the difference in the morphology of Hylamer polyethylene wear particles in comparison with PCA might have caused a more intensive biological response, early and massive osteolysis, and therefore, early loosening.

Osteorticular amyloidosis in a patient under dialysis treated by total hip arthroplasty: case report and review of the literature.

The authors present the case of a patient affected by kidney failure, who had been undergoing dialysis for several years when areas of osteolysis and bone resorption in the proximal femur and pathologic fracture appeared. She was treated surgically by hybrid total hip arthroplasty. The patient also complained of pains in other joints. The bone tissue taken from the osteolytic area was examined histologically. The test showed the presence of an amyloid substance. Microradiography and X-ray diffractometry carried out on the same samples confirmed the lack of mineralisation due to the presence of aluminum ions, presumably derived from dialysis. The high concentration of this element was confirmed by resum assay with spectrophometry in atomic absorption. Considering the results of the aforementioned tests, the patient was put on dialysis using a polymethylmethacrylate filter.

Nitric oxide synthase in tissues around failed hip prostheses.

Nineteen patients who had undergone hip revision surgery for aseptic loosening of joint prostheses were studied. Tissue samples were harvested at the interface between bone and implant, either at the stem or at the cotyle level. Immunohistochemistry was performed on tissue sections to detect nitric oxide synthase (NOS), the enzyme which enables the synthesis of nitric oxide (NO), a molecule which can activate bone resorption. Quantitative analysis of the positive cells and correlation with the presence of particulate wear debris and radiological data were performed. The authors observed a trend towards a moderate increase in positive cells due to inducible NOS in tissues containing particulate wear debris, especially of a plastic material. This increase, however, did not achieve statistical significance. On the contrary, there was a statistical correlation between iNOS (inducible NOS) and the severity of osteolysis around the prosthetic implant. Pharmacological control of the biosynthesis of NO may be considered in the prevention or treatment of loosening.

Statistical analysis in hip prosthesis evaluation.

None.

Evaluation of tissue-factor production by human endothelial cells incubated with three acrylic bone cements.

The effect of three methacrylate-based cements used for the fixation of joint prostheses on tissue-factor production by human umbilical vein endothelial cells was evaluated in vitro. The extracts in the culture medium of the cements were tested after 1-h and 7-day curing. The endothelial cells were incubated with the cement extracts for 4 h, and then the tissue factor was determined in cell lysates with both the recalcification time and enzyme immuno assay. The cements did not induce significant production of tissue factor and, therefore, did not activate the extrinsic pathway of coagulation within the limits of the mechanism considered.

Interleukin-6 expression by osteoblast-like MG63 cells challenged with four acrylic bone cements.

Periprosthetic osteolysis is a major clinical problem in total hip and total knee arthroplasty and polymethylmethacrylate (PMMA) is a possible etiologic factor. Recently, increasing importance was ascribed to interleukin-6 (IL-6) as an agent favouring bone resorption. The aim of the present study was to investigate the role of bone cements on IL-6 production by MG63. The effect of four acrylic bone cements (Sulfix-60, CMW 1, CMW 2, and CMW 3) on the protein release and mRNA expression of IL-6 in osteoblast-like cell line MG63 was examined using IL-1beta (0.2 microg ml(-1)) as the positive control. The extracts in minimum essential medium (MEM) of the cements were tested, following 1-h and 7-day curing. CMW 1 and CMW 2 significantly increased the IL-6 release into the culture media (p < 0.01). The cells incubated with Sulfix-60 and CMW 3 produced no significantly different levels of IL-6 than the basal production. A positive correlation was found between the concentration of IL-6 and the contents of benzoylperoxide (p = 0.0003) and barium sulphate (p < 0.0001). MG63 expressed IL-6 mRNA constitutively, as demonstrated by the positivity of the negative controls too. We conclude that CMW 1 and CMW 2 increase the production of IL-6 in MG63 cells. The response to Sulfix-60 and CMW 3 is not significantly greater than the negative control.

No effect of methacrylate-based bone cement CMW 1 on the plasmatic phase of coagulation, red blood cells and endothelial cells in vitro.

The compatibility of a methacrylate-based bone cement (CMW 1, DePuy International Ltd, England) used for the fixation of joint prostheses was evaluated on plasma, an erythrocyte suspension and cultured human endothelial cells. The extract of the cement was tested, following 1 hour and 7 days of curing. After the contact in vitro of the extract with plasma, activated partial thromboplastin time, antithrombin III, thrombin-antithrombin complexes and fibrin degradation products were assayed. Hemolytic activity was tested by adding the cement extracts to a suspension of erythrocytes. After 4 hours of incubation at 37 degrees C, the hemoglobin concentration was determined on the supernatants by the colorimetric method. The effect of the cement on tissue factor and thrombomodulin production was evaluated on human umbilical vein endothelial cell cultures. Tissue factor was determined in cell lysates by enzyme immunoassay, following 4 hours' incubation of cultures with the cement extract. Thrombomodulin was assayed in cell lysates by enzyme immuno assay, after 24 hours' incubation with the cement extract. The response to all trans-retinoic acid (ATRA) was tested. The cement caused no significant modifications of the coagulation tests, had no hemolytic activity, did not determine tissue factor production and did not modify thrombomodulin, compared to the negative control. The response to stimulation with ATRA was similar to that of the negative control. We conclude that the cement extract does not affect the plasmatic phase of coagulation, has no effect on erythrocytes, does not induce the expression of procoagulant activity by endothelial cells and does not impair their antithrombotic property, within the limits of the tests performed.

Evaluation of the effect of seven acrylic bone cements on erythrocytes and plasmatic phase of coagulation.

The haemolytic activity and the effect on the plasmatic phase of coagulation of seven bone cements were evaluated (Sulfix-60 from Sulzer Orthopedic Inc., a bone cement at low viscosity from Zimmer, a bone cement dough-type from Zimmer, Palacos R from Merck, CMW1, CMW2 and CMW3 from DePuy International Ltd.). Haemolytic activity was tested by adding the cement extracts in phosphate buffered saline to a suspension of erythrocytes. After 4 h incubation at 37 degrees C, the haemoglobin concentration was determined on the supernatants by colorimetric method. The effect on the plasmatic phase of coagulation was tested by adding the cement extracts in saline to human plasma. After 30 min incubation at room temperature activated partial thromboplastin time (APTT) was determined. All extracts induced non-significant variations of haemoglobin concentration and APTT. It was concluded that the tested cement extracts do not induce haemolysis and do not activate the intrinsic pathway of coagulation, at least in the tests that were performed.